Omniweb can use regular expressions to filter banner ads, or even whole web pages. You can find it in the Preferences, in the Privacy section. There are a few examples to work from, but the gist of it is:

.*\/ads\/.*

The above will match any URL that has /ads/ in it. This should match a lot of advertisements. The .* means "anything." The \/ will match a "/", because just using a "/" has a special meaning for the regular expression. Be careful, though. You could block normal web pages with this feature.

You can read more about regular expressions on the web.

[robg adds: Regular expressions, or regex, are complex but extremely powerful ... here's a Google URL to get you started with some tutorials if you're interested in learning more. You can also use regex on Mail headers, as explained in this hint.]

I may be wrong in this specific case, but if you use -regex with `find' then "\/ads\/" would find "/ads/" and "/ads/" only! that means it has to start with "/" the second letter has to be "a" etc. ".*\/ads\/.*" finds all "/ads/" even if there are other characters before or after it, e.g., "b/ads/" or "/ads/x"